1. Field of the Invention
The invention concerns an expert system capable of meeting real time constraints to take decisions based on a flow of incoming messages concerning the operation and the status of a network of machines whose status changes with time. The decisions may be applied automatically by the network of machines or may constitute a decisionmaking aid for a human expert. These two applications are complementary if the expert system encounters problems which it is not able to solve. The decisions must then be taken by a human expert but an expert system can provide invaluable help by carrying out a preliminary analysis of the problems.
2. Description of the Prior Art
The invention is concerned in particular with telecommunication network management and maintenance. The software currently used in telecommunication network management merely shows the behavior of the network by displaying alarms and the results of counts representing the respective load of each link. Management decisions and the resultant actions are the domain of a human expert.
In the field of telecommunication network maintenance it is known to use a maintenance network to centralize maintenance data produced by local maintenance software run in each switching center. This software comprises fault detecting software, periodic test software and fault locating software. The software is run either automatically or by an operator if a fault is detected.
Independent test means test the links providing the connections to the switching centers.
Local maintenance software can identify most hardware unit failures. However, this software is relatively ineffective in the case of intermittent faults or problems which are caused by slow deterioration of the hardware. For this reason it cannot provide preventive maintenance. The designers of such software cannot foresee all possible faults. Some of the knowledge needed to locate difficult faults can be acquired only through experience.
Conventional expert systems solve a problem on the basis of a fixed set of data, taking as much computation time as necessary. There may even be no limit on computation time. In the field of telecommunication network management and maintenance the expert system must make decisions on the basis of data which may even change while a decision is being made. A conventional expert system cannot handle these real time changes. A human expert must make decisions instead of the expert system if the latter is not able to make a decision, but the human expert may be swamped by a mass of data from the network of greater or lesser significance.
An object of the invention is to propose an expert system capable of solving in real time telecommunication network management and maintenance problems and capable of aiding a human expert to solve residual problems that the expert system cannot solve. This object must be achieved without modifying the existing software in the switching centers.